Method and system for television communication



June 1943. J. H. 'HoM lsHous 2,320,699

METHOD AND SYSTEM FOR TELEVISION COMMUNICATION Filed may 15, 1940{Sheets-Sheet 1' FIG I [3 J ,9 q

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Moron June 1, 1943.

J. H. HOMRIGHOUS METHOD AND SYSTEM FOR TELEVISION COMMUNICATION FiledMay 13, 1940 FIG? Flsl FIGS FIELD T 2. 7 FIGII 4-FIGIO o- FIGIO FIGSFIGS J4 4 Sheets-Sheet 2 INVENTOR.

Jime l, 1943. I J. H. HOMRIGHOUS 2,3

METHOD AND SYSTEM FOR TELEVISION COMMUNICATION Fild May 13. 1940 4Sheets-Sheet 's HALFWAVE REC.

FULL WAVE POWER HALFWAVE AMP. REC.

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' June 1, 1943. J; H. HOMRIGHOUS METHOD AND SYSTEM FOR TELE VISIONCOMMUNICATION Filed May 13, 1940 4 Sheets-Sheet 4 IN VENTOR.

Patented June 1, 1943 METHOD AND SYSTEM FOR TELEVISION COM1YIUNIGATIONJohn H. Homrighous, Oak Park, 111.

Application May 13. 1940, Serial No. 334,864

(o1. 1vs 516.).

12 Claims.

My invention relates to improvements in method and systems fortelevision'communication and particularly to systems for producingsynchronizing signals for controlling and timing. the various impulsesrequired for the production of a picture at both the transmitter andreceiver.

One of the objects of my invention is to provide improved cathode raydeflecting systems for producing interlace scanning by applying adifferent electrical condition to the vertical deflecting means inalternate fields or by changing. the time interval of every other field.

Another object of my invention is to provide a synchronizing signalgenerating mechanism for producing the various impulses" necessary forthe control of scanning in a cathode ray tube with provision foradjusting the speed of the mechanism to develop substantially widefrequency range of impulses.

Another object of my invention is the provision of synchronizing signalmechanism at the receiver which permits greater flexibility so that suchmechanism may respond to signals repre-' senting different picture ratesand also different number of lines per picture.

One of the main objects of my invention is an improved method ofaltering the number of picturechanges or frames in a given-time in orderto televise motion-picture film at 24 frames per second, or, thestandard for television practice of frames per second, or at any otherdesired number of frames per second.

Another object of my invention is the provision of a switching devicefor changing the number of horizontal lines per field or frame without]changing the frame frequency.

Another object of my invention is the provision of an element in thecathode-ray picture tube to initiate pulses of current to be used forblanking purposes or for reducing the intensity of the electron beamduring the retracing period or backward movement.

Another object of my invention is the provision of elements in thecathode-ray reproducing tube to initiate pulses of-current to blank orre.-

duce the intensity of the electron beam during the retracing period.

Another object of my invention is the provision of means forautomatically adjusting the lines horizontally in each image field.

Another object pf my invention is the provision of means sensitive tovariations of light in the reproduced images for controlling thebrightness of the images.

A feature of my invention is the generation of an alternating voltagewave and the actual transmission of this wave to the receiver wherebythe same wave form and frequency may be regenerated and otherfrequencies may also be generated from the source of power at thereceiver.

Several methods for producing interlace scanning have been devised. Onesystem, known as the even line system, requires that the up and downmovements of the cathode ray be of unequal lengtli, which has been verydiflicult'to obtain. In my present invention, I have devised a morepositive method for developing control impulses giving alternate shortand long spaced periods of time. Another system, known .as the odd linemethod, has been devised which requires a whole number of lines plus afraction of a line in each field so that the electron ray will start thesecond field at a fraction of a line distant from the start of the firstline in the first field. This system depends upon equal field length andexactly alike vertical deflecting means for all fields. In the preferredembodiment'of my in vention, I apply a different electrical condition tothe vertical deflecting means in alternate fields to shift the electronray vertically the distance equal to the space of one horizontal line.

In none of the present systems can the number of pictures in a giventime be changed from 24 to 30 pictures to televise motion picture filmat a much lower rate, 24 frames per second, than the proposed standardrate for television, 30 frames per second; as described further along.

None of the above systems show elements added to the cathode-ray tubesto initiate voltage pulses for blanking purposes.

In my prior application, Serial #306,537. filed Nov. 28, 1939, thepicture signals are combined with control and sound or audio signals insucha manner that all three are transmitted and reproduced as picture orvideo signals.

According to a preferred embodiment of my present invention, a voltagewave at the frame. frequency is generated at the transmitter, andcombined with the audio signals on a separate intermediate'carrierfrequency, which in turn is modulated on the video carrier frequency andtransmitted by radio to the receiver.

' Another advantage of my invention the generation of blanking pulses bythe pickup and viewing tubes, thereby eliminating the transmission ofthese-signals by radio and the necessary filtering equipment.

ing drawings, illustrating an embodiment thereof in which:

Figures .1 and 2 are simplified diagrammatic view of a televisiontransmitting station and a television receiving station, respectively,illustrating the principles applied in this invention.

Figure 3 is a motor device for generating control frequencies.

Figures 4 and 5 are end views of the disks shown in Figure 3 forgenerating the control or frame frequency.

Figures 6 and '7 are simplified diagrams showing the circuit figurenumbers used in generating the sweep frequencies.

Figures 8, 9, 10, and 11 show circuits used in my invention.

Figure 12 shows a circuit for identifying certain line scanning pulses.

Figure 13 shows a motor and control circuit.

Figure 14 shows an end view of disk used in Figure 13.

Figure 15 shows picture control character, reproduced at the receiver.

Figure 16 shows my improved cathode-ray pick up tube with circuitconnections.

Figure 1'7 is a top view of the mosaic used in tube shown in Figure 12.

Figure 18 shows my improved cathode-ray viewing tube with circuitconnections.

In Figure 1, the numeral I designates a cathode-ray pick up tube of theconventional type and is known as an Iconoscope. It is to be understoodthat other tubes such as the Orposite side, and an electron gun i r genrating a ray ofelectrons directed at the screen, and two sets ofdeflecting plates for deflecting the electron ray at the line and fieldfrequencies, so that it is caused to scan the screen. The picture andcertain other control characters are thereby developed and fed from oneof themetallic plates by an output connector 2 to a modulating am-,

plifier 3. The other connector 4 leads to a blanking pulse circuit Itobe further described in connection with Figur 12.

A carrier wave is provided by an oscillator. 6 in the power amplifier 1.This carrier now is power amplifier stage Il produced by the oscillatorI8. The signals from the amplifier I I are fed to the mixer circuit 9through the conductor l9.

The two carrier waves, one modulated by sweep frequency control signalsand audio signals, the other modulated by video signals.are mixed in themixer circuit 9 and fed to the common antenna 20 for transmission byradio.

The sweep control signals are transmitted in th form of sine waves,which are used to synchronize or control the scanning action with thetransmitter. The antenna 2| receives the combined carrier signals fromthe transmitter antenna 20 to a. radio frequency amplifier 22, anoscillator 23 reacts with these signals in the first stage 24 on thesuperheterodyne principle, to produce two intermediate-frequency signalswhich are fed to the two stages 25 and 26.

to cause it to scan the screen. It is to be understood, thatelectromagnetic means may be used for deflecting the electron ray. 1 Thevideo signals areapplied to a control electrode of the electron gun tochange the intensity of the electron-ray in accordance with picture orvideo signals.

In this cathode-ray tub I also provide two narrow metallic platesseparated by an insulator and placed on the right side of the tubefacing the reproduced picture. are for producing blanking pulses at thereceiver. which will be further explained in connection with Figure 18.I

'Referring to the intermediate frequency stage 26 which contains thesweep signals and the audio signals and through the action of the seconddetector 30 the output of which goes to two selective filter 3| and 32.The low frequency sweep control signals after leaving the filter 3|,still in modulated form on a carrier, are demodulated at 33 and fed tothe frequency generator 34 where the signals may be amplified andoperate a signal generator to redevelop control signals, or the signalsmay be used after suitable amplification to directly control thescanning acmodulated by the frequency band video or picture signalsthrough the modulation amplifier 3. The signals from the amplifier I aresupplied by a connection 8 to the mixing circuit 9.- Certain controlsignals are also transmitted as video signals.

The numeral l0 designates a generator for producing pulsating voltagewaves or waves of sine form for controlling the sweep frequencies at thedesired frame frequency. The low frequency sweep control voltage wavesor signals through the medium of amplifier, I I, modulates anothercarrier produced by oscillator l2 in its amplifier stage l3.

The audio or sound signals from the ruler phone ll are passed through anamplifier l5.

The sweep control signals and the audio sigapplied through a mixercircuit ii to sents a 'motor which is operated from the local tion atthe receiver which will be explained in more detail later.

The audio signal from the filter 32 is fed to the=loud speaker 35.

In Figure 2, the, numeral '36 represents what maybe called an automaticbrightness control circuit andderives its energy from the changes inbrightness of a spot or mark 31 televised from the transmitting tube anddirected into a photo-cell circuit. The output from this circuit is usedto adjust the bias on previous stages to aid in maintaining thebrightness of the reproduced picture substantially constant;

Referring to Figure 3, the numeral 38 represupply current and formallyruns at approximately 1800 R. P. M. Operated from the-motor" through theaction of a cone shaped pulley 33 and the contacting pulley 40 are twodisks of modulate a second main carrier were 1!; ill? 7i lightpolarizing material ll and 42, revolving normally at approximately 1800R. P. M. and re- These metallic plates volving past stationary pieces ofpolarizing material 43, 44, and 45 and also separate sources of light46, 41, and 48 respectively.

' The revolving and stationary members are better shown in Figures 4 and5. In Figure l the disk 42 is made up of two halves of polarisingmaterial: each half may be rotated through a very small angle and asshown on the drawings the planes of polarization are not parallel. Thisangle depending upon the desired size of the dark portion 49 or theperiod of the gap between pairs of pulses as illustrated at 56.

From the above it will be seen that when the disk 42 is rotated past thestationary member 45 and between its source of light 48 andphotoelectriccell l, that the intensity of the light reaching thephoto-cell will vary from zero to maximum value and back to zero whenrotated through approximately 180 degrees.

Referring to Figure 5 the numeral 4| represents a disk oflight-polarizing material having a certain part painted or blacked outso that rotating it in a clockwise direction past its stationarypolarized members 43 and 44 and between its sources of light 46 and 41and their respective photo-cells 52 and 53 the intensity of lightreaching each photo-cell will vary from zero value to maximum value andback to zero during one half of a revolution and during the'other halfof the revolution there will be no light change.

A system for producing the proper sweep voltages and control signals ,isshown in Figures 8 to 12 inclusive. In Figure 6 I have shown a photocell54 which may be the photo-cell 5| in Figure 3. This cell is responsiveto the variations of light intensity caused by the rotation of disk 42pre- .9, where the pulsating voltages from transformer winding 56 areinduced into the transformer secondary winding to drive the grid oftube58 positive, discharging the condenser 59 through the tube 58-. Thusby alternately charging the condenser 59 through the resistance 60 anddischarging it through the tube 58 a saw tooth voltage is circuits ofFigures 8 and 9. I may also use disk 4| ,having associated with it .twosources of light 46 and 41 and their respective photo-cells 52 and 53.These cells are responsive to the variation of light intensity caused bythe rotationof the disk 4| as previously explained.

Referring to Figure 11, I have shown a circuit for producing analternating current from the variation of light occurring in thephoto-cells 62 and 63 which may be'the photo-cells 52 and 58 shown inFigure 3. These photo-cells control the grid excitation of .grids 64 and65, of amplifier tubes 66 and 61; the anodes 68 are connected inparallel through the primary winding of transformer 69 to the positiveside of voltage divider 18. The cathodes 1| are connected in parallel toan intermediate point of the voltage divider 18. The cathode 13 ofphoto-cell 62 is connected to the grid 64 of amplifier 66 and throughresistance 14 to negative potential at the voltage divider, therebymaintaining the grid 64 at a negative potential with respect to cathode1| and plate 68'; the circuit is so arranged that an increase inthe-intensity of light on the photo-cell 62 will increase thephoto-current of tube 66. The photo-- cell 63 has its anode 15 connectedto the grid of amplifier tube 61, and it is maintained at a positivepotential with respect to its cathode 16.

winding. These control voltages from winding 69 may be induced into thetransformer winding of Figure 9 to control the vertical deflection, and

' by'changing the speedof rotation of the disk 4| the duration of thetime per field is changed so that any desired number of frames persecond may be produced.

One method or system for producing interlace scanning uses the disk 4|,Figure 5, with Figure 11, to develop impulses to trigger the sweepgenerator, Figure 9, to thereby control the vertical reciprocatingmovement of the electron ray at generated. The vertical sweep pulsesgenerated by the disk 42 in the wave forming circuits Figure 9 is fed toconductor 6| at the transmitting tube Figure l and as diagrammaticallyshown in Figure 6. The circuit of Fig. 9 is also used to produce theline sweep voltages.

From the above description it will be seen that each revolution of thedisk 42 will produce two similar impulses in the transformer winding 56to trigger the discharge tube 58. The tube 58 may be biased so that onlythe positive pulses applied to the grid will operate the tube. Sincethere is a gap 49 in the disk 42 successive impulses will occur atdifferently spaced intervals.- Changing the speed of the disk by theadjustment of the cone pulley 39 will change the picture rate withoutchanging the number of lines per picture.

The control voltages produced in Figure 8 may be transmitted to thereceiving station to govern the scanning thereat.

The pulses generated by the disk 42 can be different time, intervalswhereby one field period will be of a greater duration than the nextsucceeding field since the-dark portion on disk 4| extends through morethan an 180 degree arc. Therefore, the return trace time in alternatefields will be greater than in the intervening fields, causing afractional part of a line to be included in each field, which will havethe effect of placing the lines of alternate fields between those ofintervening fields.

From the above it will be seen that I have devised a novel method ofproducing unequal field periods of time to effect interlace scanning.

used to produce the line scanning control pulses In the preferredembodiment of my invention I use the disk I00, Figure 14, instead of thedisk 4|, with Figure 11, to develop trigger impulses at equal sp'acedperiods of time. This circuit is to be used asdiagrammaticallyillustrated in Figure '1 to develop line and fieldtrigger or control signals and a-sine form wave to modulate a carrier aspreviously explained. The circuit figure members shownin Figure-7, plusFigure 3, constitute the frequency generator shown at IU, Figure 1.

It is proposed to use frequency multiplying cirand from thesefrequencies the higher line frequencies are produced.

Referring to Figure 10, two stages of frequency multiplication areshown. The secondary'winding 18 is connected to the transformer winding88 in Figure 11 which supplies alternating pulses to the tappedsecondary and in turn to the full number of pulses or cycles to thetuned filter comprising the condenser 80 and the next transformerprimary winding 8|. This .double cycle signal is supplied by the tapedsecondary 82 to the full wave rectifier 83 where it'is again doubled andfed to the next succeeding transformer primary 8. The tapped secondary85 delivers wave rectifier tube '19 which delivers twice thealternatingcurrent to the next stage and so on until the desired high frequency forline scanning is obtained. While I have shown a circuit to double or tomultiply the frequencies, other frequency multiplying circuits may beused.

,In my invention I prefer to use the doublers and obtain 128 or 256lines per field, where each field will have exactly the same number ofpulses, therefore, the same number of lines for eachfield and to avoidinterference with local power, all that is necessary to do is toslightly change the field rate,-which will of course change the linefrequency butwill not change the number of lines per field.

With further reference to Figure 7, I have provided two switches 86 and81 for shorting out one or more stages of doublers; for instance,certain stations could be operating on 256 lines per field and otherstations on 128 lines per field. I

In order to produce or develop interlaced scan ning from a sine formvoltage: wave it is necessary to identify every other field pulse and insome manner cause the horizontal lines of one field to fall in betweenthe lines produced in the other field or the lines of one field are evennumbered and in the second field they are odd numbered. I accomplishthere features by the circuit shown in Figure 12. In this circuit,voltage waves of sine form are supplied from the circuit of Figure 11 toa full wave rectifier 86 of conventional design, which may be one stageof Fig. 10. The output wave form is shown at 81; these pulses are fedthrough the transformer winding 88 which may be the winding 8| in Fig.10 to wave forming circuit Figure 9 to drive the grid of tube 58positive discharging the condenser 59, thereby producing sawtooth formwaves "for vertical scanning as previously described. Inductivelyconnected with the transfomer winding 68 of Fig. 11 is a'half waverectifier 88, the output on the plate of amplifier 9| is adjustable,depending upon the space between lines.

The rectifier 89 and amplifier 8| will operate during eachpositive pulseto increase or decrease the potential on one of the deflecting plateswithout changingj'the potential on the opposite plate which will havethe effect of raising or lowering the horizontal lines. 4

From the above description it will be seen that I have provided anovel,and very simple means for interlacescanning or for shifting theposition of the horizontal lines scanned in a cathode-ray tube, duringalternate field pulses and which are controlled by the generator at thetransmitting station. Thus eliminating the necessity of transmitting byradio synchronizing pulses other than the one sine form wave,

At the receiver I employ the same means for identifying the positivepulses and at the same time causing the shift in the position ofhorizontal lines on the viewing tube screen.

The circuit figure numbers shown in Figure '7, omitting Figure 11, mayconstitute in one receiving station the frequency generator shown at 34,Figure 2.

From the above description it will be seen that the line pulses aredefinitely locked with the field pulses, or in other words, the samepulse that triggers the vertical deflection also supplies throughmultiplying circuits the trigger pulses for line scanning.

Furthermore, from the above description, the control of the field andline deflecting circuits at the receiver from the sine form voltage wavetransmitted by radio from the transmitting station will cause thecathode-ray or electron ray at the viewing tube to be in exactsynchronization with the cathode-ray in the pick up tube,

' in the pick up tube is focused on midpoint of line wave form is shownat 88. The current in the half wave rectifier lead can be adjusted toimpress voltage pulses on the grid of tube 9! out of .phase with thevoltage pulses developed in the fullwave rectifier 86. The anode ofamplifier 9| isconnected through the primary transformer for-theduration of each pulse and in phase with the vertical sawtooth voltagewaves. The con- .ductor 83 supplies potential through 'a centeringresistance to one verticaldeflec'ting plate. The

other vertical deflecting plate is supplied with potential from the samesource through another centering resistance not shown. The potential 75number 40, then since a single frequency or control voltage wavegenerated at the transmitter station times the deflection of both thefield and the horizontal lines at both the transmitting station andreceiving station, the cathode-ray at the viewing tube wouldautomatically be focused at the midpoint of line 40 on the screen of theviewing tube, and furthermore since I have provided through the mediumof a half wave rectifier, Figure 12, means for associating the positivepulse in each cycle of thecontrol voltage wave with a certain field, thefocused electron ray in' each tube would als'o'fall in the proper field.

The picture produced from this system will be approximately ashigh asthey are wide, since there is no necessity of reserving space at thebottom of picture for synchronizing pulses.

Another system for controlling the scanning operations at the receivingstation may comprise the motor 84, Figure 13, having control circuitsfor keeping the position of the rotor-11in step with thealtematingcurrent signals. The motor 94 drives disks or mechanismssimilar to those explained in connection with Figure 3 to in turndevelop line and field trigger potentials,

utilizing the circuits shown in Figure '7. The

motor and mechanism shown in Figure 13, to-

gether with the circuits shown in Figure 7 may constitute the frequencygenerator 34, Figure 2,

in another receiving station.

The power amplifier 95 may be supplied with signal current from thedetector 33, Figure 2. These signals after proper amplification at 95are fed to the motor 94 through contact 96 and 91. The half waverectifier 98 will supply the positive pulses to one winding of relay 99.The motor 94 is small and carries a very light load; therefore verylittle power is required to operate it. Se-

cured to its shaft are three disks of polarizing" material, two of whichare exactlylike those shown in Figures 4 and with their associatedstationary polarized members and photo-cells.

The disks are designated by the same numbers 4| and 42 and operate thecircuits shown in Figure '1, as previously explained, in connection withthe transmitting station. In the preferred embodiment of my invention Ipropose to substitute the disk I00, Figure 14, for the disk M to therebydevelop a series of trigger impulses having equally spaced periods oftime.

The third disk in Figure 13, designated I00,

and like the view shown in Figure 14 is secured to the motor shaft insuch a manner that when it is rotated one-half of a revolution to alterthe light in the photo-cell IOI (which may be substituted for thephoto-cell 54, Figure 8) to produce a pulse of current in thetransformer winding 56 of Figure 8, which is then fed to a circuitcontaining the lower winding of relay 99, in the interval between thepulses produced by rectifier 93, the rotor may be considered in stepwiththe positive pulses of the sine form voltage wave supplied to the poweramplifier 95.

The relay 99 will not operate by separate pulse 'from either therectifier 98 or photo-cell IOI.

But since the motor is two pole, the rotor may be out of step severaldegrees; in which case the relay would receive aiding pulses from boththe rectifier 98 andthe photo-cell I0I and would operate to open itscontacts at 91 which would include the resistance I02 in the motorcircuit momentarilyin order to slow its speed sufiiciently after a fewrevolutions to slip the rotor back in step with the supply current.

, From the above description it is shown that the disk secured to themotor shaft -will automatically keep in step with the current supply andthat the other disk connected to the motor shaft will also generatevoltage waves and pulses of current in exact phase relation and insynchronism with the supply. 1

This motor generator circuit or frequency generating device,,Figure 13,may be used to supply the line and frame control frequencies at thereceiver in a similar manner to that shown in Fig. 3, at thetransmitter.

When using this circuit the picture signals developed in one horizontalline may be slightly out of adjustment with the signals developed in thenext following line and to overcome this automatically I have provided ahorizontal line I03, Figure 15, which is reproduced from the permanentmark 31 at the transmitting tube, Figure 1, and will occur in allpicture changes and frames. From a point, just at the left of thishorizontal line I03, a ray of light is directed by mirror I04 andsuitable lenses to a photo-cell I05. This photo-cell may be used in thecircuit of Figure 8 which has been previouslydescribed. The transspeedlag the picture speed which will render relay I01 inoperative and give aslightly longer interval for thehorizontal' lines. However, should themotor speed lead the picture time, the mark would move to the rightcausing light to enter the photo-cell I05 which would operate relay I01momentarily to include resistance I08 in the motor circuit, therebyreducing the speed of motor. This feature has been disclosed in my priorapplication, referred to before.

The mark I03, Figure 15, also serves another purpose, that is, itautomatically controls the brightness of the picture reproduced by therefiections of the. changes in the intensity of the line or mark I03into the photo-cell I09 from the mirror. The photo-cell I09 may besubstituted for the one shown in Figure '8, whereby this circuit willfunction to adjust the bias on previous stages as shown in Figure-2 toassist in maintaining practically constant brightness in the reproducedpicture.

With reference to Figure 16, I have shown my improved pick up tube I,which improvement consists in dividing the metallic plate on the back ofthe mosaic H0 into two parts III and 2, better shown in top view, Figure17, with conductors extending from each metallic plate former winding 56would be inductively connected to the winding I06, Figure 13, whichwinding is connected through the control relay I01. The mark will moveto the left, should the motor through the tube, the mosaic may be in twoparts also, otherwise this pickup tube is of conventional design. Theconductor I I3 extending from the smaller of the two plates I II whichis located on the left side of the tube facing the front, controls thegrid excitation of grid II4 of amplifier tube H5. The anode of tube H5is connected through primary winding II6 of a transformer to positivebattery.

The operation of this circuit is as follows: As the electron beam movesfrom right to left across the mosaic IIO when scanning the image it willat the end of each scanning line he focused on a vertical image of fullheight of the picture caused by a narrow permanent fiat bar I I1, shownoutside the lens system in Figure 1. This mark will appear in all thefields, so that each time the scanning beam reaches this vertical imagea small potential change will be produced in the grid II4 of theamplifier 5, which may be further amplified in other stages, to in turnproduce a pulse of current in the primary transformer winding H6 whichis induced into the secondary transformer winding IIB to change thepotential on the control grid H9 to reduce the intensity oi. theelectron ray during the retrace period which is commonly known asblanking. These pulses, before being applied to the control grid, may beslightly delayed by well known pulse delaying methods so that theinten-' sity of the electron beam will be reduced Just at the rightinstant. I

With reference to Figure 18, I have shown a very similar arrangement tothat shown in Figure 16 for blanking the electron ray in the viewingtube at the receiver.

The element I20 on the inside of the viewing fication and as explainedfor the pick up tube. Thus at the-end of each horizontal line theintensity of the electron ray in the viewing tube is reduced for theretrace interval.

From the above description it will be seen that I have provided a verysimple and novel arrangement for blanking the electron ray in pick upand viewing tubes during the vertical and horizontal line retrace.

It will be understood that numerous modifications are possible withoutdeparting from the spirit of my invention or the scope of the claims.

Having thus described my invention, I claim: 1. In a television system,a cathode ray camera tube having an image ,plate and an electron ray'directed toward the image plate, a motor, means f or movingthe saidelectron ray to scan the said I image'plate, including mechanism drivenat adjustable speeds'by the said motor, said mechanism provided withapparatus and suitable circuits to control the movement of said electronray in vertical directions during spaced periods of time, and providedwith other apparatus and suitable circuits to control the movement ofsaid electron rayin horizontal reciprocating directions, said mechanismalso provided with a. half wave rectifier, and suitable-circuits foradjusting the said electron rayvertically, during alternate which thereis provided means including a part ofsaid image plate to control theintensity of i the said electron ray during its backward move ment.

4. The system,.in accordance with claim 1, in

which there is provided switching means to vary the number of linelocations that may be scanned on the 'said image plate in any of thesaid periods.'

5. In a television system, a cathode ray camera tube having an imageplate and an electron ray directed toward the imageplate, a motor, meansfor moving the said electron ray to scan the said imageplate, includingmechanism, driven at adjustable speeds by the saidmotor, said mechanismhaving vertical deflecting means to control the movement of saidelectron ray in vertical directions during spaced periods of time, andhorizontaldeflecting-means to control the movement of said electron rayin horizontal reciprocating directions, said mechanism also having meansfor applying 'a diflerentcondition to the said vertical deflecting meansfor alternate periods, relative to the saidvertical'deflecting means forthe intervening periods, whereby even line locations on said image plateare scanned during alternate periods and odd line locations on saidimage plate are scanned during the intervening periods.

6. The system, in accordance with claim 5, in which there is providedmeans for adjusting the speed of said mechanism to scan all linelocations on the said image plate twenty-four to thirty times persecond.

7. The system, in accordance with claim 5, in which there is providedmeans including a part of said image plate to control the intensity ofthe said electron ray during its backward movement.

8. The system, in accordance'with claim 5, in which there is providedswitching means 'tovary the number of line locations that may be scannedon the said image plate in any of the said periods.

9. In a television system, a cathode ray viewing tube, provided with animage screen, and an electron ray directed toward the image screen,

- a motor arranged to be driven by received synchronizin'g signals,means, including mechanism, driven by the said motor, for moving thesaid electron ray over the said image screen to produce successiveimages from received picture signals, said mechanism having verticaldeflecting means to control the movement of said electron ray invertical directions during spaced periods of time, and horizontaldeflecting means to control the movement of said electron ray inhorizontal reciprocating directions, said mecha-.

locations on said image screen are scanned during intervening periods. 7

10. The system, in accordance with claim 9, in which there is providedan electron ray contacting member at one edge 'of the said image screen,and means including said contacting member for controlling the intensityof the said electron ray during its backward movement. a

11. The system, in accordance with claim 9, in which there is providedswitching means to vary the number ofline locations that may be scannedon said image screen in any of the said periods. 12. The system, inaccordance with claim 9, in which there is included a mark in the saidimage. and means controlled by said mark reproduced in all images formomentarily changing the motorspeed to adjust the lines horizontally onsaid-image screen.

JOHN H. HOMRIGHOUS.

